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    <title>Document</title>
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    <!-- 使用for循环 - 求出班级里同学们平均年龄[15, 19, 21, 33, 18, 24] -->

    <script>

        let arr = [15, 19, 21, 33, 18, 24]

        let num = 0;

        for (let i = 0; i < arr.length; i++) {
            const element = arr[i];
            num += arr[i]
        }
        alert((num / (arr.length)))
    </script>
</body>

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